1. Field of the Invention
The present invention generally relates to an automated washing machine and, more particularly, to a cloth amount detecting device for use in the automated washing machine for detecting the amount of cloths put into the washing machine for washing.
2. Description of the Prior Art
In recent years the use of automated washing machines has gained wide acceptance, and the most sophisticated washing machine makes use of a cloth amount detecting device to permit the washing machine to provide an optimum water current and a process control scheme that are appropriate to the amount of cloths put into a washtub or basket and detected thereby. An example of the use of the cloth amount detecting device in the washing machine is disclosed in, for example, the Japanese Laid-open Patent Publication No. 1-119290, published May 11, 1989.
According to this publication, the cloth amount detecting device in the automated washing machine comprising a drive motor for driving a current inducing element such as, for example, a pulsator or an agitator includes an electromotive force detecting means. Specifically, the drive motor is switched on for a predetermined length of time after water has been filled in the washtub to a predetermined level, and is subsequently switched off. The electromotive force detecting means detects an electromotive force generated by the drive motor during an OFF period in which the drive motor is switched off subsequent to the ON period, that is, the predetermined length of time during which it has been switched on. The cloth amount detecting device also includes a determining means for determining the amount of cloths, put into the washtub for washing, in dependence on an output from the electromotive force detecting means.
It has, however, been found that the prior art cloth amount detecting device of the type referred to above has a problem which will now be discussed. In the system of the prior art cloth amount detecting device, since a reference cloth value utilized to compare with the actual amount of cloths to be washed is fixed to a predetermined cloth value, it often occurs that the reference cloth value does not match with the amount of cloths which the user of the washing machine has believed it ought to be, or with the amount of the cloths determined by the determining means due to a change in tension or an aging of a drive belt which is used to transmit a drive from the drive motor to the current inducing element.